
$(document).ready(function () {
    (function (root, factory) {
        if (typeof define === 'function' && define.amd) {
            // AMD. Register as an anonymous module unless amdModuleId is set
            define([], function () {
                return (root['SignaturePad'] = factory());
            });
        } else if (typeof exports === 'object') {
            // Node. Does not work with strict CommonJS, but
            // only CommonJS-like environments that support module.exports,
            // like Node.
            module.exports = factory();
        } else {
            root['SignaturePad'] = factory();
        }
    }(this, function () {

        /*!
         * Signature Pad v1.5.3
         * https://github.com/szimek/signature_pad
         *
         * Copyright 2016 Szymon Nowak
         * Released under the MIT license
         *
         * The main idea and some parts of the code (e.g. drawing variable width Bézier curve) are taken from:
         * http://corner.squareup.com/2012/07/smoother-signatures.html
         *
         * Implementation of interpolation using cubic Bézier curves is taken from:
         * http://benknowscode.wordpress.com/2012/09/14/path-interpolation-using-cubic-bezier-and-control-point-estimation-in-javascript
         *
         * Algorithm for approximated length of a Bézier curve is taken from:
         * http://www.lemoda.net/maths/bezier-length/index.html
         *
         */
        var SignaturePad = (function (document) {
            "use strict";

            var SignaturePad = function (canvas, options) {
                var self = this,
                    opts = options || {};

                this.velocityFilterWeight = opts.velocityFilterWeight || 0.7;
                this.minWidth = opts.minWidth || 0.5;
                this.maxWidth = opts.maxWidth || 2.5;
                this.dotSize = opts.dotSize || function () {
                    return (this.minWidth + this.maxWidth) / 2;
                };
                this.penColor = opts.penColor || "black";
                this.backgroundColor = opts.backgroundColor || "rgba(0,0,0,0)";
                this.onEnd = opts.onEnd;
                this.onBegin = opts.onBegin;

                this._canvas = canvas;
                this._ctx = canvas.getContext("2d");
                this.clear();

                // we need add these inline so they are available to unbind while still having
                //  access to 'self' we could use _.bind but it's not worth adding a dependency
                this._handleMouseDown = function (event) {
                    if (event.which === 1) {
                        self._mouseButtonDown = true;
                        self._strokeBegin(event);
                    }
                };

                this._handleMouseMove = function (event) {
                    if (self._mouseButtonDown) {
                        self._strokeUpdate(event);
                    }
                };

                this._handleMouseUp = function (event) {
                    if (event.which === 1 && self._mouseButtonDown) {
                        self._mouseButtonDown = false;
                        self._strokeEnd(event);
                    }
                };

                this._handleTouchStart = function (event) {
                    if (event.targetTouches.length == 1) {
                        var touch = event.changedTouches[0];
                        self._strokeBegin(touch);
                    }
                };

                this._handleTouchMove = function (event) {
                    // Prevent scrolling.
                    event.preventDefault();

                    var touch = event.targetTouches[0];
                    self._strokeUpdate(touch);
                };

                this._handleTouchEnd = function (event) {
                    var wasCanvasTouched = event.target === self._canvas;
                    if (wasCanvasTouched) {
                        event.preventDefault();
                        self._strokeEnd(event);
                    }
                };

                this._handleMouseEvents();
                this._handleTouchEvents();
            };

            SignaturePad.prototype.clear = function () {
                var ctx = this._ctx,
                    canvas = this._canvas;

                ctx.fillStyle = this.backgroundColor;
                ctx.clearRect(0, 0, canvas.width, canvas.height);
                ctx.fillRect(0, 0, canvas.width, canvas.height);
                this._reset();
            };

            SignaturePad.prototype.toDataURL = function (imageType, quality) {
                var canvas = this._canvas;
                return canvas.toDataURL.apply(canvas, arguments);
            };

            SignaturePad.prototype.fromDataURL = function (dataUrl) {
                var self = this,
                    image = new Image(),
                    ratio = window.devicePixelRatio || 1,
                    width = this._canvas.width / ratio,
                    height = this._canvas.height / ratio;

                this._reset();
                image.src = dataUrl;
                image.onload = function () {
                    self._ctx.drawImage(image, 0, 0, width, height);
                };
                this._isEmpty = false;
            };

            SignaturePad.prototype._strokeUpdate = function (event) {
                var point = this._createPoint(event);
                this._addPoint(point);
            };

            SignaturePad.prototype._strokeBegin = function (event) {
                this._reset();
                this._strokeUpdate(event);
                if (typeof this.onBegin === 'function') {
                    this.onBegin(event);
                }
            };

            SignaturePad.prototype._strokeDraw = function (point) {
                var ctx = this._ctx,
                    dotSize = typeof (this.dotSize) === 'function' ? this.dotSize() : this.dotSize;

                ctx.beginPath();
                this._drawPoint(point.x, point.y, dotSize);
                ctx.closePath();
                ctx.fill();
            };

            SignaturePad.prototype._strokeEnd = function (event) {
                var canDrawCurve = this.points.length > 2,
                    point = this.points[0];

                if (!canDrawCurve && point) {
                    this._strokeDraw(point);
                }
                if (typeof this.onEnd === 'function') {
                    this.onEnd(event);
                }
            };

            SignaturePad.prototype._handleMouseEvents = function () {
                this._mouseButtonDown = false;

                this._canvas.addEventListener("mousedown", this._handleMouseDown);
                this._canvas.addEventListener("mousemove", this._handleMouseMove);
                document.addEventListener("mouseup", this._handleMouseUp);
            };

            SignaturePad.prototype._handleTouchEvents = function () {
                // Pass touch events to canvas element on mobile IE11 and Edge.
                this._canvas.style.msTouchAction = 'none';
                this._canvas.style.touchAction = 'none';

                this._canvas.addEventListener("touchstart", this._handleTouchStart);
                this._canvas.addEventListener("touchmove", this._handleTouchMove);
                this._canvas.addEventListener("touchend", this._handleTouchEnd);
            };

            SignaturePad.prototype.on = function () {
                this._handleMouseEvents();
                this._handleTouchEvents();
            };

            SignaturePad.prototype.off = function () {
                this._canvas.removeEventListener("mousedown", this._handleMouseDown);
                this._canvas.removeEventListener("mousemove", this._handleMouseMove);
                document.removeEventListener("mouseup", this._handleMouseUp);

                this._canvas.removeEventListener("touchstart", this._handleTouchStart);
                this._canvas.removeEventListener("touchmove", this._handleTouchMove);
                this._canvas.removeEventListener("touchend", this._handleTouchEnd);
            };

            SignaturePad.prototype.isEmpty = function () {
                return this._isEmpty;
            };

            SignaturePad.prototype._reset = function () {
                this.points = [];
                this._lastVelocity = 0;
                this._lastWidth = (this.minWidth + this.maxWidth) / 2;
                this._isEmpty = true;
                this._ctx.fillStyle = this.penColor;
            };

            SignaturePad.prototype._createPoint = function (event) {
                var rect = this._canvas.getBoundingClientRect();
                return new Point(
                    event.clientX - rect.left,
                    event.clientY - rect.top
                );
            };

            SignaturePad.prototype._addPoint = function (point) {
                var points = this.points,
                    c2, c3,
                    curve, tmp;

                points.push(point);

                if (points.length > 2) {
                    // To reduce the initial lag make it work with 3 points
                    // by copying the first point to the beginning.
                    if (points.length === 3) points.unshift(points[0]);

                    tmp = this._calculateCurveControlPoints(points[0], points[1], points[2]);
                    c2 = tmp.c2;
                    tmp = this._calculateCurveControlPoints(points[1], points[2], points[3]);
                    c3 = tmp.c1;
                    curve = new Bezier(points[1], c2, c3, points[2]);
                    this._addCurve(curve);

                    // Remove the first element from the list,
                    // so that we always have no more than 4 points in points array.
                    points.shift();
                }
            };

            SignaturePad.prototype._calculateCurveControlPoints = function (s1, s2, s3) {
                var dx1 = s1.x - s2.x, dy1 = s1.y - s2.y,
                    dx2 = s2.x - s3.x, dy2 = s2.y - s3.y,

                    m1 = { x: (s1.x + s2.x) / 2.0, y: (s1.y + s2.y) / 2.0 },
                    m2 = { x: (s2.x + s3.x) / 2.0, y: (s2.y + s3.y) / 2.0 },

                    l1 = Math.sqrt(dx1 * dx1 + dy1 * dy1),
                    l2 = Math.sqrt(dx2 * dx2 + dy2 * dy2),

                    dxm = (m1.x - m2.x),
                    dym = (m1.y - m2.y),

                    k = l2 / (l1 + l2),
                    cm = { x: m2.x + dxm * k, y: m2.y + dym * k },

                    tx = s2.x - cm.x,
                    ty = s2.y - cm.y;

                return {
                    c1: new Point(m1.x + tx, m1.y + ty),
                    c2: new Point(m2.x + tx, m2.y + ty)
                };
            };

            SignaturePad.prototype._addCurve = function (curve) {
                var startPoint = curve.startPoint,
                    endPoint = curve.endPoint,
                    velocity, newWidth;

                velocity = endPoint.velocityFrom(startPoint);
                velocity = this.velocityFilterWeight * velocity
                    + (1 - this.velocityFilterWeight) * this._lastVelocity;

                newWidth = this._strokeWidth(velocity);
                this._drawCurve(curve, this._lastWidth, newWidth);

                this._lastVelocity = velocity;
                this._lastWidth = newWidth;
            };

            SignaturePad.prototype._drawPoint = function (x, y, size) {
                var ctx = this._ctx;

                ctx.moveTo(x, y);
                ctx.arc(x, y, size, 0, 2 * Math.PI, false);
                this._isEmpty = false;
            };

            SignaturePad.prototype._drawCurve = function (curve, startWidth, endWidth) {
                var ctx = this._ctx,
                    widthDelta = endWidth - startWidth,
                    drawSteps, width, i, t, tt, ttt, u, uu, uuu, x, y;

                drawSteps = Math.floor(curve.length());
                ctx.beginPath();
                for (i = 0; i < drawSteps; i++) {
                    // Calculate the Bezier (x, y) coordinate for this step.
                    t = i / drawSteps;
                    tt = t * t;
                    ttt = tt * t;
                    u = 1 - t;
                    uu = u * u;
                    uuu = uu * u;

                    x = uuu * curve.startPoint.x;
                    x += 3 * uu * t * curve.control1.x;
                    x += 3 * u * tt * curve.control2.x;
                    x += ttt * curve.endPoint.x;

                    y = uuu * curve.startPoint.y;
                    y += 3 * uu * t * curve.control1.y;
                    y += 3 * u * tt * curve.control2.y;
                    y += ttt * curve.endPoint.y;

                    width = startWidth + ttt * widthDelta;
                    this._drawPoint(x, y, width);
                }
                ctx.closePath();
                ctx.fill();
            };

            SignaturePad.prototype._strokeWidth = function (velocity) {
                return Math.max(this.maxWidth / (velocity + 1), this.minWidth);
            };


            var Point = function (x, y, time) {
                this.x = x;
                this.y = y;
                this.time = time || new Date().getTime();
            };

            Point.prototype.velocityFrom = function (start) {
                return (this.time !== start.time) ? this.distanceTo(start) / (this.time - start.time) : 1;
            };

            Point.prototype.distanceTo = function (start) {
                return Math.sqrt(Math.pow(this.x - start.x, 2) + Math.pow(this.y - start.y, 2));
            };

            var Bezier = function (startPoint, control1, control2, endPoint) {
                this.startPoint = startPoint;
                this.control1 = control1;
                this.control2 = control2;
                this.endPoint = endPoint;
            };

            // Returns approximated length.
            Bezier.prototype.length = function () {
                var steps = 10,
                    length = 0,
                    i, t, cx, cy, px, py, xdiff, ydiff;

                for (i = 0; i <= steps; i++) {
                    t = i / steps;
                    cx = this._point(t, this.startPoint.x, this.control1.x, this.control2.x, this.endPoint.x);
                    cy = this._point(t, this.startPoint.y, this.control1.y, this.control2.y, this.endPoint.y);
                    if (i > 0) {
                        xdiff = cx - px;
                        ydiff = cy - py;
                        length += Math.sqrt(xdiff * xdiff + ydiff * ydiff);
                    }
                    px = cx;
                    py = cy;
                }
                return length;
            };

            Bezier.prototype._point = function (t, start, c1, c2, end) {
                return start * (1.0 - t) * (1.0 - t) * (1.0 - t)
                    + 3.0 * c1 * (1.0 - t) * (1.0 - t) * t
                    + 3.0 * c2 * (1.0 - t) * t * t
                    + end * t * t * t;
            };

            return SignaturePad;
        })(document);

        return SignaturePad;

    }));

});
